1. Field of the Invention
This invention relates to sliders for slide fasteners having a discrete formation of coupling elements and particularly to such a slider which has means of locking the same against movement.
2. Prior Art
Conventional sliders of the type described have encountered the problem that the pull tab would flip down flat bu its own gravity to lock the slider, and not knowing this, the user would spread the fastener stringers apart to open the fastener only to damage the coupling elements. With a view to overcoming this problem, there has been proposed a certain form of slider as disclosed in Japanese Laid-Open Utility Model Publication No. 49-131001 in which the slider is equipped with a pull tab having a locking prong of slightly modified trapezoidal shape designed to prevent the prong from spontaneously or accidentally falling in between adjacent fastener elements, this prior art slider being illustrated in FIGS. 8 and 9 of the accompanying drawing. A slide fastener with this type of slider on is opened by spreading its stringer halves apart, not by lifting and not manipulating the pull tab.
However, when it is desired to lock the slider at any point on the fastener, this would become difficult as the locking prong due to its trapezoidal shape tends to depress the fastener elements from above and cannot enter between the elements unless the slider is once adjusted in position by being pulled backwards.